Washington's about to see the reopening of two newly renovated Smithsonian museums: The National Portrait Gallery and the Smithsonian American Art Museum. Both are dedicated, one way or another, to Americanness. And also to art. Forging convincing, sophisticated ties between the country and its pictures is one of their great challenges. It's also where they stand to be most interesting, even when they fail.

The museums don't manage to elucidate some essentially American culture -- because no such thing can or should exist, especially in a country as young and big and plural as this one. But they manage to do something just as important. They show the country and its artists, and even sometimes today's curators, busily constructing what it is to be American, and investing in the building of some kind of national identity. American pictures -- but only some, at certain times -- have set about defining what Americanness is supposed to be.

The whole idea of some kind of more fundamental "Americanness," seeping into all our art the way the landscape of Bordeaux seeps into its wines, falls apart as soon as you start testing it.

What if it turned out, for instance, that all of Jackson Pollock's pictures were actually painted by a Frenchman -- a certain Jacques Saint-Paul Oc -- who got a hard-drinking young American to flog them for him? Someone would be bound to insist that only a Frenchman could have managed all that insouciant paint-dripping, with its Gallic joie de vivre and a soup?on of panache .

Or how about if Pollock were German? Those angstfully expressionist canvases, painted just after the destruction of World War II, clearly speak of a flattening of everything that came before, of protean foundations that could lead to either equal-opportunity democracy or leveling communism.

Could his pictures even be Canadian? A snowstorm of paint, but also a happy mixing of many different forces to produce a pleasant unity.

Of course, it could indeed be that Pollock's art is American. But who could ever say for sure, merely from looking at it?

As anthropologist Michael Herzfeld put it, speaking from his office at Harvard, Americans have "the assumption that if we are all members of the nation-state, we're in some transcendent way alike" -- but that is an assumption, he says, that he and his colleagues have been questioning for years. He acknowledges that their doubts have yet to hit the country's mainstream culture.

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In our National Portrait Gallery, the quest for an American identity happens quite explicitly. The museum is officially dedicated to talking about America through its "significant" Americans; saying anything about the art that shows them -- even as an emblem of "Americanness" -- comes a distant second. The gallery's pictures of Americans don't even have to be by Americans to get on the walls. Edgar Degas, working at his most French, does the job just fine -- so long as his Gallic talents are being used to reveal an American as significant as Mary Cassatt. (Though she spent most of her working life in Paris as one of the official French impressionists, and Degas painted her there.)

The fact that there's no claim that the art is especially American, or even especially good -- only a tiny fraction of its artists come anywhere close to Degas -- doesn't simplify the museum's artful task of using it to give us a big-picture view of America.

Curators have dedicated a deluxe suite of galleries to the nation's presidents. Many scholars, however, would say that such a "great man" view of history shortchanges the true shapers of a country. It neglects the nameless people who find new ways to till the land and raise their kids and work assembly lines -- and who, in America especially, are supposed to be the ones who choose the leaders tasked with realizing the public's dreams.